Piezoelectric Resonator with Two Layers

Microelectromechanical systems (MEMS) filters have advantages in being able to reduce the size, weight, and power required when used as part of electronic systems such as radios; however, MEMS-type filters have limitations. For example, thickness MEMS-type filters (e.g., thickness-extensional mode piezoelectric resonators) are typically limited to a single operating frequency per substrate die. Also, lithographically determined operating frequency resonators cannot meet low-impedance specifications.